EW can share an exclusive excerpt from the book below.
Initially, they thoughtAmanda Seyfriedwas their Regina George, before ultimately circling back to McAdams in the role.
ButUgly BettystarAmerica FerreraandTwo Broke GirlsactressKat Denningswere also both heavily favored for the role.

Lacey Chabert, Lindsay Lohan, Rachel McAdams, and Amanda Seyfried in ‘Mean Girls’.Everett Collection
So Fetchis bursting with never-before-revealed stories and details from the making ofMean Girlsand its enduring cultural impact.
Waters knew McAdams would crush it, but something even more interesting happened when the two actresses came together.
Not only did McAdams inhabit the lines perfectly, she also seemed to intimidate Lohan.

Lizzy Caplan in ‘Mean Girls’.Paramount/courtesy Everett
She was verging on stardom, and it was emanating from her.
In his experience with Lohan so far, she usually dominated everyone, commanded a room.
When she was with McAdams, that changed.

So Fetch: The Making of Mean Girls.courtesy amazon
But Waters couldnt resist the dynamic hed witnessed between Lohan and McAdams.
When Sherry Lansing saw McAdams as Regina, she fell in love with the actress.
She thought McAdams would make the perfect Queen Bee.
She was rivetingly beautiful, Lansing remembers, and such a good actress.
One of Lansings executives protested that McAdams was too old.
Let me explain something, Lansing said.
This age discussion made her tense.
At nearly sixty, it seemed absurd to her.
She doesnt look twenty-five.
So I dont care how old she is.
But, the executive said, what if it got out that McAdams was older?
What difference does it make if it gets out?
Franzese, a wise and confident twenty-five, interjected: Id go with the merlot.
He seemed like the answer to their Damian problem.
They didnt want someone to play the Gay Kid.
They wanted someone to play Damian.
When the room was ready, Seyfried went first and nailed it.
Fey and Waters loved her, even though theyd ultimately cast McAdams as Regina.
She was freaky, Waters says of Seyfrieds approach to Regina.
She did a whole different take on it.
It was kind of like this weirdly spooky girl who just had strange thoughts.
She had this inner life.
Producer Lorne Michaels actually preferred her for the role of Regina but was outvoted in the end.
Then Franzese came in to read and bombed.
All of the personality theyd just seen in the waiting room had evaporated.
Where had that funny, confident, easy-to-talk-to guy gone?
Now he seemed to be just playing a character, but theyd liked the real guy better.
Damian had become a problem.
But the others on theMean Girlsteam werent on board with Williams.
The table read was coming up in Los Angeles, and they had to make a call.
The filmmakers and executives debated among themselves and with outside confidants.
Paramount executive John Goldwyn insisted, He cant feel like a club kid.
They didnt want Damian to be too cool, which could have been a problem with Williams.
Fey was having trouble because she had such a clear idea of the character in her head.
He was sweet and Italian, perfect for the part.
Thats not exactly me, Hol- brook said.
Franzese really wanted the role, which could have been what threw him off.
He wouldnt have been the first amiable actor to choke on nerves at the crucial moment.
Damian would be a dream role for him.
Franzese seemed like the obvious choice, except for that one tiny matter of bombing his audition.
Her role presented its own share of challenges.
(This is, it must be said, a funny play on the word catty.)
She goes on to explain to Cady that Regina George is a selfish, backstabbing, slut-faced ho-bag.
She drives the entire plot by using Cady as a pawn in a scheme to psychologically torture Regina.
But Caplan presented as sharp, smart, and sarcastic in her audition, someone to root for.
She had a star quality that would make Janis likable no matter what she did.
Would anyone believe her as an outcast?
When Waters confronted her about this problem in the audition, she shrugged.
Look, she said, Ill goth myself out.
She said it with such confidence that he believed her.
She loved Charles Bukowski and had dyed her hair black in high school.
She would happily dye it again and flat-iron it into wild spikes to get this job.
Hed see for sure if it worked when she showed up for the table read.
Even with all of that mostly settled, Liroff still had huge parts to fill.
She had yet to find the right combination for Reginas two Plastics sidekicks, Gretchen and Karen.
Further throwing the casting off, the script described her as gangly.
Liroff had to abandon that particular idea quickly in hopes of getting the right actress.
Ashley Tisdale, Vanessa Hudgens, and Mary Elizabeth Winstead tried out but still werent quite right.
The character has a specific timing in terms of comedy, Liroff says.
And shes this wannabe.
Its a fine line to play.
Liroff didnt know what she was going to do until Lacey Chabert walked into her office.
Chabert didnt think she was right for the part at all, given the physical description.
Chabert had a petite, five-foot- two, hourglass figure.
But she said of the character, I loved how insecure she was.
Born in Purvis, Mississippi, Chabert came to herMean Girlsaudi- tion at age twenty with an already-packed resume.
Be- fore herMean Girlsaudition, she had rarely displayed her comedy skill.
Most of her work had leaned dramatic, especially given the melodrama ofParty of Five.
As Reginas gossipmongering confidante, shes key to the movies success.
She was a revelation in herMean Girlstryout.
Liroff could immediately see that Chabert understood the complicated role and was a gifted comedic actress.
Once he saw it, he immediately agreed.
He had never considered anyone else seriously for the role, but ChabertwasGretchen.
They cast Chabert in late September 2003, with an October start date for the production looming.
Liroff still needed to cast the role of Karen at that point.
Lively was the most likely candidate at that point, but Liroff was moved to keep looking.
Waters kept returning to Seyfried, who had a quality he wanted on-screen.
And Michaels, who had loved Seyfrieds tape, put the pieces together.
As the filmmakers talked about Seyfried yet again, he said, What about the dumb girl?
Do you think she can play that?
When they brought Seyfried back in to read for Karen, everything fell into place.
Nobody else had kind of found that weird airy thing she had, Waters says.
The filmmakers saw interesting potential in casting her as the dippy Karen Smith.
And it doesnt really work that way.
Youre meant to find someone that is incredibly sharp so they can actually play that.
Seyfried grew up in Allentown, Pennsylvania, where shed just graduated from high school.
She had modeled as a child, in a campaign for Limited Too and on young adult book covers.
Youve got to picture a ten-year-old wanting to be Cindy Crawford, she said of her modeling career.
I didnt know what that meant.
She landed on the daytime soapsAs the World TurnsandAll My Children.
She put off higher education, never to return.
Copyright 2023 by Jennifer Armstrong.
From Dey Street Books, an imprint of HarperCollins Publishers.